I think you mean Roy Bird Cook. That was one of Robertson's sources, and in a footnote he highlights at least one place where Cook contradicted himself in two different writings.One of my favorites is The Family and Early Life of Stonewall Jackson by George Bird Cook. There are several editions of this, including the first in 1924. I don't remember where got mine but I do remember that it was hard to find. I probably paid way too much for it, but it has material you literally won't find anywhere else, including in Robertson. Cook covers Jackson's prewar life in tremendous detail but also includes a chapter about the war years. If you are mostly interested in Jackson the person rather than Jackson the general, this book is for you (provided you can find it).